Humans Respond to Scent of Fear

Moviegoers might want to scoff a bit less when characters
talk about the scent of fear. Women exposed to fear chemicals in male sweat
tended to see ambiguous faces as being more fearful, according to a new study.

Such research shows for the first time how even
the smell of fear can affect how people interpret what they see right in
front of them. That fits with previous studies showing that visual and facial
cues can affect human emotion and interpretation – but mainly when the
situation seems uncertain.

Male participants watched neutral clips, slapstick comedies
and horror flicks, while a gauze pad sat in their
armpits to collect sweat. Later, female participants had the gauze pads
held under their noses as they watched images of faces that changed from
somewhat happy to neutral to somewhat fearful.

Researchers chose males as sweat donors because of their
larger apocrine sweat glands. The male volunteers used only scent-free shampoo,
conditioner and soap provided by the lab several days beforehand, and kept a
diet journal to avoid odorous foods such as garlic, onion and asparagus.

The study also used female respondents because of their
better sense of smell and higher sensitivity to emotional cues. A first
experiment involved 48 females who sniffed gauze that contained "fear
sweat" from the horror film sessions, gauze that contained sweat from the
slapstick comedy viewings, and control gauze that contained no sweat. A second experiment
with 16 females focused on the "fear sweat" gauze and control gauze.

Women volunteers ended up more likely to interpret ambiguous
faces as fearful when they were smelling the "fear sweat," but only
in the case of ambiguous faces. They still interpreted somewhat happy or
somewhat scared
faces according to what they saw.

Humans rely primarily on sight and hearing, so it's no
surprise that smell only comes into play in situations where the other senses
are less certain. Animals often rely on their more sophisticated sense of smell
as a common form of communication, and even humans may fall back on it during
certain social situations.

"The sense of smell guides our social perception when
the more-dominant senses are weak," Chen said.

Fear isn't all that may tweak human noses. Chen previously looked
at a very different situation involving guys, gals and "sexual sweat."

Live Science Staff

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